Acta Zoologica Cracoviensia, 20() 1975
Biology, Ecology, and Economic Importance of Cassids (Coleoptera, Chrysomelidae, Cassidinae) of the Ojców National Park
Abstract:
Investigations carried out in the years 1966-1971 on a meadow in the Sąspowska Valley in the Ojców National Park showed that the maximum length of life of cassids was not one year, as was previously believed, but almost 4 years in the case of Cassida rubiginosa Müll., 3 years with C. vibex L. and C. viridis L., and 2 years with C. flaveola Thunbg.; females living always longer than males. The highest fecundity occurs with 1-year old females (200-350 eggs) decreasing with 2- and 3-years old specimens. The emergence and development of cassids depend on physical factors (temperature, insolation, rains, wind) while the biotic factors (parasites, predators, microorganisms) play a decisive role in the reduction of development stages of these beetles. In relation to the initial number of eggs the total reduction was very high (98.00-99.50 per cent). The investigated species of cassids have essential economic importance. C. rubiginosa Müll, and C. vibex L. strongly attack Cirsium arvense, C. viridis L. — Mentha arvensis, Stachys palustris, and Galeopsis pubescens, and С. flaveola Thunbg. — Stellaria media, moreover, it was found that C. nebulosa L. and C. nobilis L. attack Chenopodium album, while Hypocassida subferruginea Schrnk. damages Convolvulus arvensis. The above mentioned species of cassids reproduce easily and in masses under laboratory conditions, their complete development taking as little as 30 days, hence real possibility exists of using imalagines and larvae of these species for biological control of troublesome field weeds.
